In its first week of availability, the demo for Ensemble's Halo Wars was downloaded by over two million users.

That's according to Microsoft, as it claims that more people joined the Xbox Live service in January than any other month. Fable II Knothole Island and Fallout 3: Operation Anchorage were two of the top performers.

The company also noted that third party Xbox 360 software generated USD 139 million in sales during January, as Valve's Left 4 Dead was the fourth highest seller for the month.